Apparatus for mounting an electronic component

ABSTRACT

A method of and apparatus for mounting an electronic component at a specified position of an object. The method includes applying a sealant in a first application process. The sealant is quickly, sufficiently and forcibly applied in the first application process simply by avoiding electrodes at the arrangement position, and tightly contacting the arranged electronic component and the object. Then the bonding of the electrodes is performed in the usual manner. A second application process is carried out by applying a sealant to the periphery of the electronic component in the same manner as in the convention method, which is sufficient to cause the sealant to flow to the sealant previously applied under the electronic component. The second application process can be accordingly conducted speedily and sufficiently. Air bubbles will not be trapped between the electronic component and the object, with the result that mounting failures due to breakage or corrosion of the electronic component can be reduced. Only a short period of time is required to apply the sealant even though it is applied twice, so that production time is shortened and production efficiency is improved.

TECHNICAL FIELD

The present invention relates to a method for mounting an electroniccomponent by means of arranging and sealing of the electronic componenton an object such as a circuit board to which the component is mountedand, an apparatus and a dispenser used in the method.

BACKGROUND ART

A technique called as COB (CHIP ON BOARD) has attracted attention inrecent years, as a way of mounting electronic components on a circuitboard, in which electronic components are mounted onto electrodes on acircuit board in a state of the electronic components faced downward.The COB technique will be described with reference to the drawings.

FIG. 10A is a flow chart of the conventional COB method. Based on thisfigure, the description is made. Referring first to FIG. 10B, accordingto the conventional COB method, an electronic component b is firstarranged and bonded to a circuit board d. Electrode parts c as shown inFIG. 10B are provided on the circuit board d for the electric connectionto the electronic component b. The circuit board d is held at a stage ain FIG. 10B. Meanwhile, electrode parts of the electronic component bhave bumps e to be bonded with the electrode parts c of the circuitboard d. Each bump e is coated with a silver paste or the like for thebonding. The electronic component b is transferred while being sucked bya nozzle f, and positioned at an arrangement position on the board d.After the electronic component b is arranged on the board d, the silverpaste is fused by heat thereby to bond the electronic component.Thereafter, a sealant is applied in the periphery of the electroniccomponent b as indicated in FIG. 10C. The sealant i is applied by adispenser h along a higher position side of the electronic component bafter the circuit board d is held slantwise with the use of, forinstance, an inclination stage g shown in FIG. 10C. In this manner, theapplied sealant i is allowed to flow to a lower portion of theelectronic component b along the inclination of the circuit board d. Thesealant i is set with heat to complete the bonding. Reference symbol jin FIG. 10C indicates a positioning base for positioning the circuitboard d.

The conventional method as above finds difficulty in flowing the sealanti to the lower portion of the electronic component b, because a gapbetween a lower face of the electronic component b and the circuit boardd is as narrow as several tens μm, and moreover the sealant i is highlyviscous. A feed time for the flow of sealant i is consequently apt to belengthy, in other words, production time is lengthened thereby loweringproduction efficiency. Besides, the sealant i fed to the gap tends to beinsufficient in feed amount, resulting in the formation of air bubbleswhich are to be enclosed. When the air bubbles are present between thecomponent b and the circuit board d, and the periphery of the electroniccomponent b is sealed to tightly close the gap between them, anexpansion/shrinkage of the air in the bubbles will occur due to changeof the surrounding temperature. A pressure increase or decrease due tothe expansion/shrinkage of air bubbles sometimes invites breaks of theelectronic component b or the humidity in the air bubbles causescorrosion of the electrode or the like, thus leading to mounting faults.

The present invention is devised to solve the aforementioned issues, andhas for its object to provide a method for mounting an electroniccomponent by applying a sealant beforehand at an arrangement position ofthe component on an object where the electronic component is to bemounted thereby to positively apply the sealant under the electroniccomponent, so that the electronic component can be sealed quickly andsufficiently with the occurence of breaks, corrosion or the likemounting failures being reduced, thereby improving productionefficiency, and an apparatus and a dispenser used in the method.

SUMMARY OF INVENTION

In order to accomplish the above-described objective, a method formounting an electronic component according to a first aspect of thepresent invention comprises:

a first application process of applying a sealant to a position of anobject to which an electronic component is to be mounted where theelectronic component is to be arranged, in a manner to avoid anelectrode part of the object;

a bond process of arranging and bonding the electronic component at thearrangement position; and

a second application process of applying a sealant at least partly toperiphery of the electronic component after bonded onto the object.

According to a second aspect of the present invention, in the firstaspect, at least the first application process among the first andsecond application processes uses a writing method.

According to a third aspect of the present invention, in the firstaspect, the first application process uses a screen print method.

According to a fourth aspect of the present invention, in any one of thefirst-third aspects, different sealants are used in the first and secondapplication processes.

According to a fifth aspect of the present invention, in the fourthaspect, the sealant in the first application process has heat cyclefunction and moisture resistance and resists being mingled with airbubbles, while the sealant in the second application process smoothlyfits to a bump of an electrode part of the electronic component, and hasgood fluidity and low surface tension.

According to a sixth aspect of the present invention, in any one of thefirst-fifth aspects, the sealant in the first application process ismultifunctional epoxy, while the sealant in the second applicationprocess is one selected from silicone, flame retardant epoxy and acrylicresin.

According to a seventh aspect of the present invention, an apparatus formounting an electronic component is provided, which comprises:

a holding device for holding an object to which the electronic componentis to be mounted;

a first applying device for applying a sealant to an arrangementposition of the object held by the holding device where the electroniccomponent is to be arranged, in a manner to avoid an electrode part ofthe object;

a bonding device for arranging and bonding the electronic component atthe arrangement position of the object; and

a second applying device for applying a sealant at least partly toperiphery of the electronic component after bonded on the object.

According to an eighth aspect of the present invention, in the seventhaspect, at least the first applying device among the first and secondapplying devices is a writing device.

According to a ninth aspect of the present invention, in the seventhaspect, the first applying device is a screen printing device.

According to a 10th aspect of the present invention, in any one of theseventh-ninth aspects, different sealants are used in the first andsecond applying devices.

According to an 11th aspect of the present invention, in the 10thaspect, the sealant used by the first applying device has heat cyclefunction and moisture resistance and resists being mingled with airbubbles, while the sealant used by the second applying device smoothlyfits to a bump of an electrode part of the electronic component, and hasgood fluidity and low surface tension.

According to a 12th aspect of the present invention, in any one of theseventh-11th aspects, multifunctional epoxy is used as the sealant usedby the first applying device, while one selected from silicone, flameretardant epoxy, and acrylic resin is used as the sealant used by thesecond applying device.

According to a 13th aspect of the present invention, in any one of theseventh-12th aspects, the first applying device has a dispenser equippedwith a plurality of discharge openings for the sealant, and controldevices for controlling discharge amounts of the sealant from thecorresponding discharge openings individually.

A dispenser according to a 14th aspect of the present invention is usedin the mounting apparatus in any one of the seventh-13th aspects, whichhas a plurality of discharge openings, wherein sealant feed paths areprovided individually to the corresponding discharge openings.

According to a 15th aspect of the present invention, in any one of thefirst-sixth aspects, a thickness of the sealant applied in the firstapplication process is not smaller than a height of the electrode of theelectronic component and a height of the electrode of the object.

According to a 16th aspect of the present invention, in any one of theseventh-13th aspects, a thickness of the sealant applied by the firstapplying device is not smaller than a height of the electrode of theelectronic component and a height of the electrode of the object.

In the first aspect of the present invention, the electronic componentis arranged at the position of the object to which the electroniccomponent is to be mounted and where the sealant is applied beforehandin the first application process. The sealant is quickly, sufficientlyand forcibly applied in the first application process simply by avoidingthe electrode at the arrangement position, to be in tight contact withthe arranged electronic component and the object, and then, withoutcausing any obstruction to a successive bonding of electrodes of theelectronic component and the object, the bonding of the electrodes isperformed usually. In the second application process, the sealant isapplied to the periphery of the electronic component in the same manneras conventionally, which is enough to send a sealant to the sealantapplied beforehand under the electronic component. The secondapplication process is accordingly conducted speedily and sufficiently.Air bubbles are hard to mingle with the sealant between the electroniccomponent and the object, whereby mounting failures due to breakage orcorrosion of the electronic component because of the air bubbles can bereduced. The sealant is applied each time in a short time althoughapplied twice, so that a production time is shortened and productionefficiency is improved. The first application process serves to bond theelectronic component arranged thereafter to the circuit board, andtherefore the electronic component is prevented from being displacedafter the arrangement. Moreover, the electronic component is bonded andsealed with improved performance, whereby a yield and product qualityare enhanced.

In the second and eighth aspects of the present invention, anapplication locus and a movement speed in the writing method can be setfreely, thereby to easily cope with any arrangement of electrodes on theobject. Moreover, any required application density and applicationamount are satisfied with ease. Particularly, the writing methodutilized in the first application is effective to reduce mountingfailures furthermore. Since an application position of the sealant iscorrectly controlled, even the sealant of low viscosity does not flow tothe electrodes and thus does not hinder the bonding of electrodes once asafe gap is properly secured to the electrodes. The low viscous sealantimproves working efficiency further owing to its good fluidity.

In the third and ninth aspects of the present invention, any arrangementof electrodes on the object is coped with by the print pattern setbeforehand to a screen, and a required application density is ensured,whereby mounting failures are decreased furthermore. The sealant can beapplied instantaneously simply by opening/closing the screen and movinga squeegee to a plurality of electronic component arrangement positionsat one time. Working efficiency is improved furthermore.

The fourth-sixth and 10th-12th aspects of the present invention can copewell with different application conditions such as different applicationmethods, different instruments, etc. between the first and secondapplication processes. Thus, each of the first and second applicationscan be performed well.

According to the seventh aspect, when the first applying device movesthe dispenser, e.g., in three dimensions to the object held by theholding device, the sealant can be applied to the arrangement positionexcept the electrode. Thereafter, the electronic component is arrangedto the arrangement position by the bonding device. As a result, thebonding operation can be performed while the electrodes of theelectronic component and the object confront each other without beingdisturbed by the sealant. Then, by the second applying device, thedispenser is moved and the sealant is applied to the periphery of thebonded electronic component, so that the sealing is completed. The mountmethod is hence carried out automatically.

According to the 13th aspect of the present invention, since the feedamounts of the sealant to the plurality of discharge openings arecontrolled individually, the application amount of the highly viscoussealant by the whole of the dispenser can be finely and correctlycontrolled to fit to a variety of application conditions in an optimummanner. If the discharge amount of the sealant from each dischargeopening is controlled with a position of the discharge opening takeninto consideration, the application amount can be effectivelycontrolled, for instance, so that when the application locus is curved,the application amount is small at an inner side of a curved applicationlocus and large at an outer side of the application locus, that is, tobe uniform as a whole.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects and features of the present invention willbecome clear from the following description taken in conjunction withthe preferred embodiments thereof with reference to the accompanyingFigures in which:

FIG. 1A is a flow chart of a method for mounting an electronic componentaccording to a first embodiment of the present invention;

FIGS. 1B, 1C, 1D are perspective views showing a state when each processis executed with the use of an apparatus employed in the mounting methodof the first embodiment;

FIG. 2 is a perspective view of an applying device, employed in a firstapplication process in the first embodiment, carrying out an applicationoperation;

FIG. 3 is a perspective view of an arranging device, employed in anelectronic component arrangement-bond processes in the first embodiment,arranging an electronic component;

FIG. 4 is a perspective view of an applying device, employed in a secondapplication process in the first embodiment, performing an applicationoperation;

FIG. 5 is a sectional view of a dispenser employed, during a writingoperation, in the applying device of FIG. 2 of the first embodiment;

FIG. 6 is a perspective view of a moving mechanism for moving each ofthe two applying devices and the arranging device in the firstembodiment;

FIG. 7 is a perspective view of the whole of a mounting apparatus whichis capable of carrying out the mounting method in the first embodiment;

FIG. 8 is a sectional view of a dispenser used in a mounting method anda mounting apparatus according to a second embodiment of the presentinvention;

FIG. 9 is a sectional view of an application operation conducted by anapplying device used in an applying process of a mounting method and amounting apparatus utilizing a screen printing method according to athird embodiment of the present invention; and

FIGS. 10A, 10B, 10C are a flow chart of a conventional mounting methodof sealing an electronic component and perspective views of an apparatusused in two processes of the method.

DETAILED DESCRIPTION OF THE INVENTION Best Mode for Carrying Out theInvention

Before the description of the present invention proceeds, it is to benoted here that like parts are designated by like reference numeralsthroughout the accompanying figures.

Embodiments of the present invention will now be described withreference to FIGS. 1 through 9.

First Embodiment

FIGS. 1 through 7 show a mounting method and a mounting apparatusaccording to a first embodiment of the present invention. As indicatedin FIGS. 1B-1D, the first embodiment is related to mounting of anelectronic component 2 to an object, e.g., a circuit board 1 on whichthe component is to be mounted. A mounting apparatus for the component 2which comprises a positioning base 3 as a holding device 11 as shown inFIGS. 1B, 1C, 2, 3 for positioning and holding the circuit board 1, abonding device using, for example, a suction nozzle 4 as shown in FIG.1C as a bonding device 6 for arranging and bonding the electroniccomponent 2 onto the circuit board 1, and a first sealant applyingdevice 7 having a dispenser 5 arranged so as to be movable over thecircuit board 1 in three dimensions as shown in FIGS. 1B, 2. Although itis satisfactory to position the bonding device 6 and the first applyingdevice 7 at the same stage of the same machine, these devices may bepositioned at different stages, or may be provided as individualmechanical devices to be used sequentially. According to the firstembodiment, a second applying device 10 having an inclined stage 8 and adispenser 9 as shown in FIGS. 1D and 4 is also used to conduct the sameseal process as in the prior art to the periphery of the electroniccomponent 2 after being bonded. The inclined stage 8 employs apositioning base 13 although the positioning base 13 may be differentfrom the working stage used by the bonding device 6 and first applyingdevice 7. The positioning base 13 is specifically provided to positionthe circuit board 1 in an inclined attitude without any shift ormovement, and therefore the positioning base 13 has special positioningparts 13 a, 13 b. Each positioning part 13 a is constructed of a pair ofpins for positioning one corner part of the board 1, and eachpositioning part 13 b is constituted of an L-shaped member to positionone corner part of the board 1.

For example, the holding device 11 may be used for operations in thebonding device 6, first applying device 7 and second applying device 10.In that case, the holding device 11 holds the circuit board 1 in theinclined state each operation or inclines the circuit board only whenthe sealant is applied after the circuit board is bonded.

The first and second applying devices 7, 10 are different devices in thefirst embodiment. In the event that the working stage is shared,preferably, a common device is used for the first and second applyingdevices. Also preferably, each of the dispensers 5, 9 of the first andsecond applying devices 7, 10 is moved back and forth and positionallycontrolled in X, Y directions that are orthogonal to each other on ahorizontal plane and in a vertical Z direction that is orthogonal to thetwo directions for the application work, as shown in FIGS. 2, 3. A knownXY robot as indicated in FIG. 6 is used therefor. FIG. 6 shows, as oneexample, an XY robot 100 for the first applying device 7. Referencenumeral 101 denotes a Z-direction driving mechanism for moving the firstapplying device 7 up and down in the Z direction, 102 denotes anX-direction driving mechanism for moving back and forth in the Xdirection the first applying device 7 supported by the Z-directiondriving mechanism 101, and 103 denotes a Y-direction driving mechanismfor moving the X-direction driving mechanism 102 back and forth in the Ydirection.

Naturally, the application of the sealant with the use of the applyingdevice 7 is preferred to be performed by a writing device adapting awriting method in order to secure application accuracy. A highlyaccurate operating mechanism 15 and a highly accurate operation controldevice 16 are used. As a known example of the writing device, a writingdevice is disclosed in the published specification of Japanese Laid-OpenPatent Publication No. 2-181494 which includes a cam mechanism rotatedby a motor and having a dispenser (discharge nozzle) for dischargingsealant from a discharge opening set in a movable fashion to be close toand away from a face to be written, and a moving device, equipped with apiezoelectric element, for moving the dispenser. Although the operationcontrol device 16 may be a special controller, a microcomputer that canperform numerical control is convenient in terms of general andmanagement of numerical values. In comparison with the writing method,the application by the applying device 10 is simple, therefore requiringan operating mechanism 17 and an operation control device 18 which arelower-grade than those set in the applying device 7. In other words, notso highly accurate, conventional ones are employed in the applyingdevice 10.

Not only is an inclination angle (θ) of the inclined stage 8 changeable,but an angle (α) for holding the circuit board 1 can be changed. A mostefficient application operation is provided through free setting of theangles θ and α. Specifically, θ is 15° and α is 45° when an epoxy phenolsealant of 150,000 cPs (at ordinary temperatures) is used.

The mounting apparatus according to the first embodiment is illustratedin FIG. 7 in which 90 is a storage area for the boards 1 before beingmounted, 91 is a carrier device for carrying the boards 1 one by onefrom the storage area 90, 92 is a motor for moving a carrier part 91 ato work positions for a first application process, an arrangementprocess, a second application process while the boards 1 are loaded onthe carrier part 91 a which is a part of the carrier device 91, 93 is aguide for guiding the movement of the carrier part 91 a, 94 is a movingbody supporting the carrier part 91 a and being movable back and forthalong the guide 93 by the motor 92, 95 is an inclining mechanism forinclining the whole of the moving body to a predetermined angle, and 97is a storage area for storing mounted boards 1. By way of example, FIG.7 shows a state in which the nozzle 4 of the bonding device 10 is set tothe Z-direction driving mechanism 101 of the XY robot of FIG. 6. Theinclining mechanism 95 includes the inclined stage and can incline theboard 1 to the predetermined angle.

The electronic component 2 is mounted with the use of the above mountingapparatus, for example, by a method in accordance with a flow chart ofFIG. 1A. The method will be described hereinbelow. As shown in FIGS. 1Band 2, a sealant 21 is applied to a position 20 of the circuit board 1where the electronic component 2 is to be arranged, so as not to beapplied to an electrode part 22 of the circuit board 1. This is a firstapplication process and is carried out as widely and densely as possiblein a predetermined thickness by the writing method referred to earlier,in the range where the sealant is not applied to the electrode part 22.The thickness of the sealant is not smaller than an interval definedbetween a bump and an electrode, so that it is preferable that a spaceis not present between a lower face of the electronic component 2 and asurface of the sealant 21 on a surface of the circuit board 1. Morespecifically, as an example, if the bump is 50 μm high and the electrodeis 2 μm high, the sealant 21 is preferably at least 50 μm or higherwhich is the height of the bump because the electrode has the very smallheight of 2 μm, and more preferably, 52 μm or higher. An upper limit ofthe thickness of the sealant 21 is determined so that the sealant doesnot obstruct a connection between the electronic component 2 andconfronting electrode of the circuit board 1 when the electroniccomponent 2 is bonded to the circuit board 1. In the above example, theupper limit of the thickness of the sealant 21 is preferablyapproximately 55 μm. A writing locus and a locus density by thedispenser 5 are suitably set so as to control the thickness of thesealant 21 as above. The writing is performed in the first embodiment tolinearly reciprocate the dispenser 5 continuously with a fine pitch asindicated in FIGS. 1B and 2. Needless to say, the present invention isnot limited to this.

In the first application process, a predetermined distance is securedbetween the circuit board 1 and a leading end of the dispenser 5 by aspacer 23 as shown in FIG. 5. The sealant 21 supplied to the dispenser 5is discharged out through a discharge opening 5 a by a pressure ofcompressed air 24 fed from a compressor 200. Simultaneously with thedischarging, the dispenser 5 is driven to write in the above-describedmanner to the circuit board 1. At this time, a thermostatic water 25 iscirculated in the periphery of the dispenser 5 to prevent a viscositychange of the sealant 21. Although the first embodiment uses the spacer23, a distance-securing device such as the spacer 23 or the like can beeliminated in the event that the circuit board 1 and dispenser 5 arehighly accurately held in a state parallel to each other, for instance,as disclosed in Japanese Laid-Open Patent Publication No. 2-187095, etc.and at the same time the sealant 21 is not required to be accurate withregard to the application amount. As a specified example, the distanceis, e.g., 80-100 μm.

Then, as shown in FIGS. 1C and 3, the electronic component 2 is arrangedso as to be bonded by the bonding device 6 at the arrangement position20 of the circuit board 1 after the sealant is applied. As a result ofthe bonding, the electrodes 22 of the circuit board 1 and the electrodesof the electronic component 2 are connected with each other via bumps125 of the electronic component 2. The bonding is executed in the samemanner as in the prior art, and therefore the detailed description willbe omitted here. For this arrangement-bond process, the nozzle 4 iscontrolled to move in X, Y directions that are orthogonal to each otheron the horizontal plane and in a vertical Z direction by an operatingmechanism 26 and an operation control device 27. Driving mechanisms forthe control may be the same as employed in the applying device.

A second application process is performed by a second applying device 10shown in FIGS. 1D and 4. Since the process is not different from theconventional one, the detailed description will be omitted. The sealant21 is set by heat, and then the procedures are completed.

In the above-described manner, the electronic component 2 is mountedautomatically by the mounting apparatus to the circuit board 1,including the seal process.

According to the above mounting method, the sealant is forcibly appliedquickly and sufficiently in the first application process simply byavoiding the electrodes 22 that are present at the arrangement position20 and, by becoming brought into tight contact with the electroniccomponent 2 and circuit board 1. Therefore, the process does not hinderthe subsequent bonding of electrodes of the electronic component 2 andthe circuit board 1, and then the bonding is performed in the usualmanner. When the sealant 21 is applied to the periphery of theelectronic component 2 in the second application process similar to theprior art, it is enough to apply the sealant 21 to the sealant that areapplied beforehand under the electronic component 2, and therefore theprocess can proceed speedily and sufficiently. Since it is difficult forair bubbles to enter the sealant 21 between the electronic component 2and circuit board 1, mounting failures resulting from breaks orcorrosion of the electronic component 2 because of the air bubbles canbe lessened. Further, the sealant 21 can be applied in a short period oftime although applied twice, thereby shortening the production time andimproving production efficiency. The first application processeffectively works and bonds the succeeding electronic component 2arranged thereafter to the circuit board 1, so that the electroniccomponent 2 is prevented from being displaced after the arrangement, andthe fixing function of the bonded and sealed electronic component 2 canbe improved. Accordingly, the yield and product quality are improved.

Since the application locus and movement speed can be set freely in thewriting method, the method copes readily with any arrangement of theelectrodes 22 on the circuit board 1, and thereby to easily meets anyrequired application density and application amount. Particularly thewriting method used in the first application process further lessensmounting failures. Since the application position of the sealant 21 canbe controlled correctly, once the safety gap for the electrode 22 is setadequately, even the sealant having a low viscosity never flows to theelectrodes and thus never obstructs the bonding, but enhances workingefficiency more because of the low viscosity and good fluidity.Specifically, for example, while the prior art needs a sealant ofapproximately 150,000 cPs viscosity, one example of the first embodimentcan use a sealant of 5000 cPs viscosity in the first application processand 5000 cPs viscosity in the second application process.

In other words, different sealants can be used in the first and secondapplication processes, so that the sealants can be employed withdifferent application conditions such as different methods or differentinstruments, in the first and second application processes, resulting inimproved performance of the first and second applications. Specifically,for example, one that is superior in heat cycle function and moistureresistance and can eliminate air bubbles is selectable as the sealant inthe first application process, while one that smoothly fits to thebumps, has good fluidity, low surface tension and high reliability canbe selected as the sealant in the second application process. Morespecifically, multifunctional epoxy can be used as the sealant for thefirst application, and silicone, flame retardant epoxy or acrylic resinetc. can be used as the sealant for the second application.

The second applying device 10 is illustrated in an inclined staterelative to the board 1 in FIG. 4. However, the device 10 is not limitedto this position, and may be disposed so as to be orthogonal to thesurface of the board 1.

Second Embodiment

FIG. 8 shows a dispenser 5 which is particularly suitable for a firstapplication process in a mounting method and a mounting apparatusaccording to a second embodiment of the present invention. The dispenser5 has a plurality of discharge openings 5 a for the sealant 21. In thesecond embodiment, three discharge openings 5 are provided and arrangedin one row. However, the present invention is not restricted to thisarrangement and a proper number of the discharge openings may bearranged in any manner.

The discharge openings 5 a are connected to solenoid valves 33 a, 33 b,33 c by joints 31 and air tubes 32 respectively. Reference numerals 34,35 in FIG. 8 indicate a cap of the dispenser 5 and an air leakprevention seal, respectively. The solenoid valves 33 a, 33 b, 33 c areconnected to regulators 36 a, 36 b, 36 c, respectively. Each of theregulators 36 a, 36 b, 36 c can regulate the pressure of air suppliedfrom a compressor 201. Therefore, the discharge amount of the sealant 21from each discharge opening 5 a can be adjusted individually byadjusting the regulators 36 a, 36 b, 36 c and adjusting opening/closingof the solenoid valves 33 a, 33 b, 33 c. Thus, the regulators 36 a-36 b,solenoid valves 33 a-33 c function as a discharge amount control device.

In the above construction, since the sealant 21 can be discharged fromthree discharge openings 5 a to a central part and both side partsthereof, the discharged sealant 21 assumes a rectangular section,thereby eliminating a minute step of the thickness in a breadthwisedirection of the sealant 21 which is peculiar to the writing method. Thesealant can be applied flat in the breadthwise direction into a trulyrectangular cross section. By applying this construction in to the firstapplying device 7 of the first embodiment, the first application processcan be achieved, and by apply the same construction to the secondapplying device 10 of the first embodiment, the second applicationprocess can be accomplished. The construction is thus efficient when onedispenser is shared for the first and second application processes. Thedispenser 5 of the second embodiment can also be adapted to othergeneral applications.

When the feed amount of the sealant 21 to the plurality of dischargeopenings 5 a is controlled individually as above, the discharge amountof the whole dispenser 5, that is, the application amount by the wholedispenser 5 can be minutely and correctly controlled even if the sealant21 has a high viscosity, e.g. nearly 150,000 cPs, which hence enablesvarious application conditions in an optimum state. By controlling ofthe discharge amount of the sealant 21 from each discharge opening 5 aand taking into consideration the position of the discharge opening, theapplication amount can be controlled so as to be small at an inner sideof a curved application locus and large at an outer side of theapplication locus, and thus the sealant can be applied uniformly as awhole.

Third Embodiment

FIG. 9 indicates a screen printing device for carrying out a firstapplication process in a mounting method and a mounting apparatusaccording to a third embodiment of the present invention.

This operation will be described. The circuit board 1 is held on a stage41 serving as the holding device. A screen 43 patterned by an emulsion42 is positioned so as to agree with a wiring pattern of the board 1.The sealant 21 is placed on the screen 43. The sealant 21 is applied onthe circuit board 1 by moving a squeegee 44 held in pressed contact withthe screen 43. The above is the same as a general method of screenprinting. Nearly the same operation and effect as achieved in the firstembodiment are realized in the first application process.

In comparison with the writing method whereby the sealant 21 is appliedflat in the breadthwise direction, an edge of the pattern of theemulsion 42 formed on the screen 43 is sharpened and is easily separatedfrom the screen. The third embodiment can achieve approximately the sameeffect although it is inferior to the writing method.

The method of the third embodiment can meet any arrangement of theelectrodes on the circuit board 1 by the print pattern set beforehand onthe screen 43 by the emulsion 42 and moreover, a required applicationdensity is fulfilled. Accordingly, defective mounting can be furtherreduced. Besides, the sealant 21 can be applied instantaneous simply byopening/closing the screen 43 and moving the squeegee 44, and applied atone time to arrangement positions of a plurality of electroniccomponents 2, thereby improving production efficiency further.

As is made clear from the foregoing description of the presentinvention, the sealant is applied at the mounting position of theelectronic component before the electronic component is positionedthereon. Therefore, mounting failures such as breaks, corrosion or thelike caused by application faults of the sealant, e.g., enclosure of airbubbles, etc. can be reduced, and production time can be improved.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying figures, it is to be noted that various changes andmodifications will be apparent to those skilled in the art. Such changesand modifications are to be understood as included within the scope ofthe present invention as defined by the appended claims unless theydepart therefrom.

What is claimed is:
 1. An apparatus for mounting an electroniccomponent, said apparatus comprising: a holding device for holding anobject on which the electronic component is to be mounted; a firstapplying device, for applying a sealant to an arrangement position ofthe object being held by the holding device, the arrangement positionbeing a position on the object where the electronic component is to bearranged, wherein the sealant has a heat cycle function and moistureresistance and resists being mingled with air bubbles; a bonding devicefor arranging and bonding the electronic component at the arrangementposition of the object; and a second applying device for applying asealant to at least a portion of the periphery of the electroniccomponent after being bonded on the object, wherein the sealant smoothlyfits to a bump of an electrode part of the electronic component, and thesealant has good fluidity and low surface tension, wherein differentsealants are used in said first and second applying devices, and whereinsaid first applying device includes a dispenser having a plurality ofsealant discharge openings, and a plurality of control devices forindividually controlling discharge amounts from the discharge openings,respectively.
 2. An apparatus for mounting an electronic component, saidapparatus comprising: a holding device for holding an object on whichthe electronic component is to be mounted; a first applying device, forapplying a sealant to an arrangement position of the object being heldby the holding device, the arrangement position being a position on theobject where the electronic component is to be arranged, wherein thesealant has a heat cycle function and moisture resistance and resistsbeing mingled with air bubbles; a bonding device for arranging andbonding the electronic component at the arrangement position of theobject; and a second applying device for applying a sealant to at leasta portion of the periphery of the electronic component after beingbonded on the object, wherein the sealant smoothly fits to a bump of anelectrode part of the electronic component, and the sealant has goodfluidity and low surface tension, wherein different sealants are used insaid first and second applying devices, and wherein said first applyingdevice comprises a plurality of sealant paths terminating in a pluralityof discharge openings, respectively.
 3. An apparatus for mounting anelectronic component, said apparatus comprising: a holding device forholding an object on which the electronic component is to be mounted; afirst applying device, for applying a sealant to an arrangement positionof the object being held by the holding device the arrangement positionbeing a position on the object where the electronic component is to bearranged, wherein the sealant has a heat cycle function and moistureresistance and resists being mingled with air bubbles, a bonding devicefor arranging and bonding the electronic component at the arrangementposition of the object; and a second applying device for applying asealant to at least a portion of the periphery of the electroniccomponent after being bonded on the object, wherein the sealant smoothlyfits to a bump of an electrode part of the electronic component, and thesealant has good fluidity and low surface tension, whereinmultifunctional epoxy is used as the sealant in said first applyingdevice, and one selected from silicone, flame retardant epoxy, andacrylic resin is used as the sealant in said second applying device,wherein said first applying device includes a dispenser having aplurality of sealant discharge openings, and a plurality of controldevices for individually controlling discharge amounts from thedischarge openings, respectively.
 4. An apparatus for mounting anelectronic component, said apparatus comprising: a holding device forholding an object on which the electronic component is to be mounted; afirst applying device, for applying sealant to an arrangement positionof the object being held by the holding device, the arrangement positionbeing a position on the object where the electronic component is to bearranged, wherein the sealant has a heat cycle function and moistureresistance and resists being mingled with air bubbles; a bonding devicefor arranging and bonding the electronic component at the arrangementposition of the object; and a second applying device for applying asealant to at least a portion of the periphery of the electroniccomponent after being bonded on the object, wherein the sealant smoothlyfits to a bump of an electrode part of the electronic component, and thesealant has good fluidity and low surface tension, wherein said firstapplying device includes a dispenser having a plurality of sealantdischarge openings, and a plurality of control devices for individuallycontrolling discharge amounts from the discharge openings, respectively.5. An apparatus as claimed in claim 4, wherein each of said controldevices comprises: a regulator for regulating air pressure; and asolenoid valve communicating with said regulator and said respectivedischarge opening.
 6. An apparatus as claimed in claim 4, wherein saidfirst applying device comprises a plurality of sealant paths terminatingin a plurality of discharge openings, respectively.
 7. An apparatus asclaimed in claim 4, wherein said first sealing device is adapted toapply the sealant in a thickness that is not smaller than a combinedheight of the electrode of the electronic component and the electrode ofthe object.
 8. An apparatus for mounting an electronic component, saidapparatus comprising: a holding device for holding an object on whichthe electronic component is to be mounted; A first applying device, forapplying a sealant to an arrangement position of the object being heldby the holding device, the arrangement position being a position on theobject where the electronic component is to be arranged, wherein thesealant has a heat cycle function and moisture resistance and resistsbeing mingled with air bubbles; a bonding device for arranging andbonding the electronic component at the arrangement position of theobject; and a second applying device for applying a sealant to at leasta portion of the periphery of the electronic component after beingbonded on the object, wherein the sealant smoothly fits to a bump of anelectronic part of the electronic component, and the sealant has goodfluidity and low surface tension, wherein said first applying devicecomprises a plurality of sealant paths terminating in a plurality ofdischarge openings, respectively.
 9. An apparatus for mounting anelectronic component, said apparatus comprising: a holding device forholding an object to which the electronic component is to be mounted; afirst sealant applying device including a dispenser having a pluralityof discharge openings and a plurality of control devices forindividually controlling discharge amounts of sealant from the dischargeopenings, wherein said first applying device is adapted to apply thesealant to an arrangement position on the object where the electroniccomponent is to be arranged while avoiding an electrode part of theobject; a bonding device for arranging and bonding the electroniccomponent at the arrangement position of the object; and a secondapplying device for applying a sealant to at least a portion of aperiphery of the electronic component after being bonded onto theobject.
 10. An apparatus as claimed in claim 9, wherein said secondapplying device is a writing device.
 11. An apparatus as claimed inclaim 10, wherein the sealants, used in said first and second applyingdevices, are different types of sealants.
 12. An apparatus as claimed inclaim 11, wherein the sealant used in the first applying device has heatcycle function and moisture resistance and resists being mingled withair bubbles, and the sealant used in said second applying devicesmoothly fits to a bump of an electrode part of the electronic componentand has good fluidity and low surface tension.
 13. An apparatus formounting an electronic component as claimed in claim 10, wherein thesealant used in the first applying device is a multifunctional epoxy,and the sealant used in the second applying device is one selected fromsilicone, flame retardant epoxy, and acrylic resin.
 14. An apparatus asclaimed in claim 9, wherein the sealants, used in said first and secondapplying devices, are different types of sealants.
 15. An apparatus asclaimed in claim 14, wherein the sealant used in the first applyingdevice has heat cycle function and moisture resistance and resists beingmingled with air bubbles, and the sealant used in said second applyingdevice smoothly fits to a bump of an electrode part of the electroniccomponent and has good fluidity and low surface tension.
 16. Anapparatus for mounting an electronic component as claimed in claim 14,wherein the sealant used in the first applying device is amultifunctional epoxy, and the sealant used in the second applyingdevice is one selected from silicone, flame retardant epoxy, and acrylicresin.
 17. An apparatus for mounting an electronic component as claimedin claim 9, wherein the sealant used in the first applying device is amultifunctional epoxy, and the sealant used in the second applyingdevice is one selected from silicone, flame retardant epoxy, and acrylicresin.
 18. An apparatus for mounting an electronic component as claimedin claim 9, wherein said bonding device includes a suction nozzle.